1. Field of the Invention
This invention relates to a hybrid IC device having wide dynamic range in which wider dynamic range has been achieved through the use of a plurality of monolithic ICs.
2. Description of the Related Art
With the wider dynamic ranges being implemented in monolithic ICs in recent years, hybrid IC devices are being used in which monolithic ICs are incorporated in a variety of forms. The prior art is now discussed with reference to the drawings.
The structure of a monolithic IC is first described with reference to FIG. 9, which is a cross-sectional view of an npn transistor formed inside a monolithic IC. In FIG. 9, a collector 74, emitter 75, base 76, epitaxial layer 77, imbedded layer 78, and isolation diffusion layers 79a and 79b are formed on the same p+ type substrate 80 to configure the pnp transistor. The collector 74, emitter 75, epitaxial layer 77, and imbedded layer 78 consist of n+ type silicon, while the base 76 and the isolation diffusion layers 79a and 79b consist of p+ type silicon. Also, the collector 74, emitter 75, and base 76 are provided with a collector electrode 71, emitter electrode 72, and base electrode 73, respectively, made of aluminum.
The npn transistor depicted in FIG. 9 is electrically insulated from adjacent regions by the isolation diffusion layers 79a and 79b. Such active elements (i.e. transistors or diodes) as this are formed inside monolithic ICs.
The monolithic IC is mounted on a mounting board 13, soldered through a vapor-deposited film 81 onto a substrate electrode 82 consisting of copper foil, and operated with the potential of the substrate 80 as the lowest potential.
Next will be described, with reference to FIG. 10, an example amplifier circuit that is implemented with such monolithic ICs, in a conventional IC device made up of a combination of such monolithic ICs.
In FIG. 10, a monolithic IC 1 is mounted by soldering on a mounting board 13, as in FIG. 9. The monolithic IC 1 is an amplifier circuit that is configured with differential amplifier circuitry. It is provided with a positive highest potential electrode terminal 4, a negative highest potential electrode terminal 5, a substrate electrode terminal 14, a positive signal input terminal 9, a negative signal input terminal 11, a positive signal output terminal 10, a negative signal output terminal 12, and a ground electrode terminal 8. The ground electrode terminal 8 is connected to a ground electrode on the mounting board 13. The negative highest potential electrode terminal 5 and the substrate electrode terminal 14 are connected to a negative highest potential power supply terminal 7 on the mounting board 13, by means of which connections, all of the elements provided inside the monolithic IC operate normally without operating at a potential below that on the substrate electrode terminal.
The characteristic dynamic range of the monolithic IC 1 is determined by the characteristic dynamic ranges of each of the active elements inside it, and by the minimum value of the dynamic ranges produced between all of the active elements and the substrate electrode terminal 14. This characteristic dynamic range is the highest voltage that may be applied across the positive highest potential electrode terminal 4 and the substrate electrode terminal 14.
The monolithic IC 1 processes those signals input from the positive signal input terminal 9 that are higher than the potential on the ground electrode terminal 8, and outputs the results thereof on the positive signal output terminal 10. And it processes those signals input from the negative signal input terminal 11 that are lower than the potential on the ground electrode terminal 8, and outputs the results thereof on the negative signal output terminal 12. In other words, if the potential on the ground electrode terminal 8 is 0 V, only positive signals will be output on the positive signal output terminal 10, and only negative signals will be output on the negative signal output terminal 11.
If the characteristic dynamic range of the monolithic IC 1 is 100 V, then, ordinarily, the potential V4 on the positive highest potential electrode terminal 4 will be +50 V and the potential V14 on the substrate electrode terminal 14 will be -50 V. That is, the monolithic IC 1 is operable within a range of from V4 (=+50 V) to V14 (=-50 V).
In a conventional hybrid IC device configured by combining monolithic ICs, as described above, each of the monolithic ICs operates independently. Therefore, in cases where the AC signal plotted in FIG. 11A is input on both the positive signal input terminal 9 and the negative signal input terminal 11 of the monolithic IC 1, when the absolute value of the input signal voltage exceeds a certain value, the output signal from the positive signal output terminal 10 and the output signal from the negative signal output terminal 12 will be saturated and distorted, with V4 (=+50 V) and V14 (=-50 V), as plotted in FIGS. 11B and 11C, respectively. The reason for this is that the monolithic IC 1 is unable to output an output signal the absolute value of which exceeds 50 V.
An object of the present invention is to implement, by means of innovatively connecting the monolithic ICs, a hybrid IC device exhibiting a wide dynamic range wherewith no distortion is produced in the output signals.